HAWK: THE BLOCKCHAIN MODEL OF CRYPTOGRAPHY AND PRIVACY-PRESERVING SMART CONTRACTS

Download here : Hawk: The Blockchain Model of Cryptography and Privacy-Preserving Smart Contracts

Source : https://eprint.iacr.org/2015/675.pdf

Extract from Abstract

Emerging smart contract systems over decentralized cryptocurrencies  allow  mutually  distrustful  parties  to  transact safely  without  trusted  third  parties.  In  the  event  of  contractual  breaches  or  aborts,  the  decentralized  blockchain  ensures that honest parties obtain commensurate compensation. Existing systems,  however,  lack  transactional  privacy.  All  transactions, including   flow   of   money   between   pseudonyms   and   amount transacted,  are  exposed  on  the  blockchain.We present Hawk , a decentralized smart contract system that does  not  store  financial  transactions  in  the  clear  on  the  blockchain, thus retaining transactional privacy from the public’s view.A Hawk programmer  can  write  a  private  smart  contract  in  an intuitive manner without having to implement cryptography, and our  compiler  automatically  generates  an  efficient  cryptographic protocol where contractual parties interact with the blockchain, using  cryptographic  primitives  such  as  zero-knowledge  proofs. To   formally   define   and   reason   about   the   security   of   our protocols,  we  are  the  first  to  formalize  the  blockchain  model of cryptography. The formal modeling is of independent interest. We advocate the community to adopt such a formal model when designing  applications  atop  decentralized  blockchains.

Author Details


Ahmed Kosba, Andrew Miller at University of Maryland and Cornell University
{akosba, amiller}@cs.umd.edu, {rs2358, zw385}@cornell.edu, cpap@umd.edu